There have been known image projection devices such as head-mounted displays (HMDs) that directly project an image onto the retina of the user by using a light beam emitted from a light source (Patent Document 1). Such image projection devices employ a method called Maxwellian view. In Maxwellian view, the light beam forming an image is made to be converged on the vicinity of the pupil to project the image onto the retina.
It has been known to move the display area when the user moves the face to move the visual line (Patent Document 2). It has been known to adjust the position of the screen in response to the change in posture of the wearer (Patent Document 3). It has been known to perform adjustment so that the image light enters the pupil when the pupil moves (Patent Document 4).